1. Field of the Invention
The present invention relates to a semiconductor optical device.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 11-103088 describes a waveguide type light receiving device. This light receiving device includes an optical attenuator and an optical detector that are arranged in the direction of light propagation. The optical detector has a first optical absorption layer, and the optical attenuator has the second optical absorption layer. In the light receiving device, light that propagates through the second optical absorption layer is incident on the first optical absorption layer. The optical attenuator is optically coupled to the optical detector.